Step 2: Preparation of methyl 3-oxo-3-pyridin-2-ylpropionate; NaH (60% mineral oil suspension; 30 g, 750 mmol, 2.5 eq.) was suspended in cyclohexane (900 mL) and the temperature was raised to reflux. To this suspension 2-acetylpyridine (36 g, 300 mmol) was added dropwise for 10 minutes followed by dimethyl carbonate (100 mL, 1.2 mol, 4 eq.). The reaction mixture was heated to reflux for 4 hours, followed by standing at room temperature overnight and then cooled to 0 °C. The near-solid mixture was quenched by adding a solution of AcOH (75 mL) in water (250 mL), followed by dilution with Et2O (250 mL) and stirring until all solids were completely dissolved. The aqueous layer was separated and extracted with Et2O (2 x 250 mL). The organic extracts were combined, dried with MgSO4 and concentrated under reduced pressure. The crude product was purified by distillation to afford the recovered 2-acetylpyridine (40 °C/0.3 mbar; 6.5 g, 18%) and the target product methyl 3-oxo-3-pyridin-2-ylpropionate (105 °C/0.6 mbar; 27.5 g, 51%).
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